Rheostat-switch



(No Model.)

J. P. MOLAUGHLIN.

RHEOSTAT SWITCH.

-No. 433,359. Patented July 29, 1890.

1.4: q 5 2 2 WITNESSES: v INVENTOR W ames M L MM,

M Attgrncg UNITED STATES JAMES F. MCLAUGHLIN, OF

PHILADELPHIA, PENNSYLVANIA.

RH EOSTAT-SWITCH.

SPECIFICATION forming ,part of Letters Patent No. 433,359, dated July 29, 1890. Application filed December 4, 1889. Serial No. 332,528- (No model) To all whom it may concern:

Be it known that 1, JAMES F. MOLAUGHLIN, a citizen of the United States, and a resident of Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented certain new and useful Improvements in Rheostat-Switches, of which the following is a specification.

My invention has reference to improvements in electric switches, and more especially to improvements in switches used in connection with rheostats, although the same is not absolutely confined to such switches as distinguished from others.

The main object of the invention is to provide a cheap and convenient device in which the contacts between the switch-arm and the contactblocks shall be maintained by a spring-pressure, so that the wear of either of them shall not produce what is known in the art as a bad or loose contact, causing an increased transition resistance at these points, and the consequent heating, and in many cases burning, of the said contacts.

Other advantages resulting from myconstruction will appear from the detailed description of the same, in which reference is made to the accompanying drawings, in which I have shown, in-

Figure 1, a top plan view of my improved rheostat-switoh; in Fig. 2 an inverted plan view of the same with a portion of the switchlever broken away, and in Fig. 3 a sectional view on line :20 0a of Fig. 2.

Referring to the said drawings, there is shown a base-plate 1, the same being a metal skeleton casting, semicircular in form, with a raised boss 2 in the center thereof. This base 1 has formed upon its upper surface and near the curved edge thereof a semi-annular groove 3, rectangular in cross-section and opening into a slot 3', which is divided, for the sake of stiffness, into a number of segmental slots by bridge-pieces or webs 4. Into the groove 3 is inserted, so as to closely fit the same, a semi-annular strip 5, of insulating material, and while any kind of insulating material may be used for this purpose I use, by preference, slate, glass, soapstone, or other refractory substances. The semi-annular insulating-strip 5 is screwed to the casting 1 by the screws 6 6, passing through the webs 4:. This strip of slate or other insulating material has formed upon its upper surface a semiannular groove 7, which in cross-section also appears rectangular, and seated in said groove and upon the upper surface of the strip 5 are the contact-blocks S 8, &c.,which are segmental in general outline, and the inner ends of which are formed by enlargements S. The under side ofv each contact-block is formed with two ledges, as shown, which rest upon the upper surface of the strip of insulating material, while the short segmental projection thereby produced on the under side ofeach contact-block is received in and closely fits the groove 7.

Screws 9, passing through the strip of insulating material into each contact-block from below, secure the latter to the frame, so that each contact-block is securely fastened to the supporting insulating-strip by a single screw. The enlarged inner end of each contact-block constitutes the contact-surface of the same, as will presently appear, and when the parts are assembled, as shown, the inner surfaces of the contact blocks are all portions of the surface of a cylinder described about the cen ter of the boss 2 of the casting 1.

Upon the boss 2, the upper end of which is formed into a journal, as shown in Fig. 3, there is mounted a brush-lever 10, which for this purpose is provided with a boss 10, formed into a journal-bearing, as shown. The inner or short arm of the brush-lever is enlarged, and in said enlargement is produced a socket 11, opening into an offset 12, and a contact brush block 13 is located in said socket and offset, it being formed for this purpose with a stem 14, which enters the socket, and in which is also seated a helical spring 15, the tendency of which is to force the contact brush-block outwardly and into firm contact with the blocks 8 8. It will now be seen that when the brush-lever is turned in either direction the contact brush-block 13 will bear forcibly upon the different contact-blocks in succession, so that an electric current passing between the brush-lever and either of the contact brush blocks will experience very little resistance at the contact-surfaces, while at the same time the lever can be moved with ease from point to point, owing to the yielding of the contact brush-block. On the casting 1 there is also mounted a segment 16, (upon posts 16,) provided with V-shaped stopnotches 17 17 around its edge. The outer portion of the brush-lever is also enlarged, and in said enlargement is formed a socket 18, in which is seated a sliding pin 19, backed I by a helical spring 20. This pin 19 is shaped at its outer end into a V-shaped tooth 21, and it will now be seen that when the brush-lever is in such position that the contact brushblock fully bears upon any one of the contact;- blocks 8 the stop-tooth 21 will engage one of the stop-notches '17, and will thereby arrest and maintain the brush-lever in this position, from which it can only be moved by the application of a slightly-greater force, by which the stop-tooth riding over the inclines of the stop-notches is withdrawn. It is of course understood that the stop-n otches are properly spaced for this purpose.

In the casting there are provided a number of holes 22 for screwing the device to a table or wall by screws 23, and one of these screws 23 may serve as a binding-post, to which one terminal of the circuit-wire 24 is attached, another circuit-wire being attached to one terminal contact-block, as shown.

To each screw 9, and consequently to each contact-block 8, is secured a wire 25, which wires form the terminals of suitable resistance-coils, which are properly graduated so as to constitute a rheostat in the ordinar Y manner. These resistance-coils are shown diagrammatically in the drawings, and the course of the current entering the apparatus by the circuit-Wire 24 is in the direction of the arrows indicated in the drawings.

Having now fully described my invention, I claim and desire to secure by Letters Patent- 1. In a rheostat-switch, the combination of a series of segmental contact-blocks and a switch-lever carrying a spring-seated brushblock in operative relation to the contactblocks, with a notched segmental plate, and a spring-seated stop-tooth carried by the switch-lever for engaging the notches,-and thereby locking the lever in position, substantially as described.

2. In a rheostat-switch, the combination of a series of segmental contact-blocks insulated from each other, with a switclrlever having a recess and a spring-actuated brush-block seated therein, a second recess formed in the lever, with a spring-actuated stop-tooth seated therein, and a notched disk in operative relation to the stop-tooth, substantially as described.

I11 testimony "whereof I have signed my name to this specification in the presence of two subscribing witnesses.

J AMES F. MCLAUGHLIN.

Witnesses:

EDWIN F. GLENN, CHAS. B. M ACKIN. 

